The program we wish to pursue is designed to examine the behavioral consequences of rearing kittens in selected visual environments and with selected perturbations of opportunity to move in light. Perceptual capacities are assessed by using standardized tests of visually coordinated movement and standardized discrimination procedures and by examining all animals on the same set of problems. The assessment of behavior will be supplemented by electrophysiological determination of receptive field characteristics of units in the visual system. The special visual environments include; absence of visual stimulation; stimulation only with diffused light; intermittent stimulation with a strobe light; restriction of movement of visible contours to one direction; absence of linear contours and stimulation only from point sources; normal, unrestricted exposure. The perturbations of opportunity to move in light include: absence of opportunity to locomote; locomotion with eye immobilized or partially immobilized; locomotion with surgically induced rotation of one eye, or surgically induced squint; disruption of compensatory eye movements which normally accompany locomotion by destruction of the vestibular apparatus. BIBLIOGRAPHIC REFERENCES: Cynader, M., Berman, N., and Hein, A. Cats raised in a one-directional world: effects on receptive fields in visual cortex and superior colliculus. Exp. Brain Res. 22: 267-280, 1975. Blakemore, C., Van Sluyters, R.C., Peck, C.K., and Hein, A. Development of cat visual cortex following rotation of one eye. Nature 257: 584-586, 1975.